我正在尝试构建一个角度为10的库，但是我遇到了问题。 在角度9时效果很好。
当项目从角度9迁移到角度10时，会发生此问题。
[error] TypeError: Cannot read property 'toString' of undefined
at new Input (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/postcss/lib/input.js:53:20)
at parse (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/postcss/lib/parse.js:13:15)
at new LazyResult (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/postcss/lib/lazy-result.js:60:16)
at Processor.<anonymous> (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/postcss/lib/processor.js:138:12)
at Processor.process (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/postcss/lib/processor.js:117:23)
at StylesheetProcessor.process (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/ng-packagr/lib/styles/stylesheet-processor.js:47:46)
at Object.readResource (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/ng-packagr/lib/ts/cache-compiler-host.js:80:57)
at TsCompilerAotCompilerTypeCheckHostAdapter.loadResource (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/@angular/compiler-cli/src/transformers/compiler_host.js:504:37)
at Object.get (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/@angular/compiler/bundles/compiler.umd.js:28507:94)
at DirectiveNormalizer._fetch (/opt/fms/Control-Viewer-Iom/iolm-control-lib/node_modules/@angular/compiler/bundles/compiler.umd.js:20345:47)